The present invention relates to a safety arrangement for an elevator door opening.
A safety device used in an elevator door opening is a foot guard, also called a toe guard, placed at the lower edge of the elevator car and having a length substantially at least equal to the width of the landing door opening. The toe guard is a plate-like piece or equivalent mounted in a substantially vertical plane, and it is designed to block the gap opening into the elevator shaft between the lower edge of the elevator and the floor surface of the landing e.g. when the elevator has stopped due to a failure so that the lower edge of the elevator car remains above the surface of the landing floor. This gap may be so large that a person escaping from the elevator can fall through the gap into the elevator shaft when descending from the car remaining above the surface of the landing floor. Likewise, without a toe guard there is a risk that a person who is working on a landing and loading or unloading e.g. a freight elevator remaining somewhat above the landing floor may inadvertently get so near the elevator shaft that his toes are in the shaft space. If the elevator car starts moving downwards in such a situation, there is a risk of the person's toes being injured. A toe guard functioning as a safety device prevents the occurrence of this type of hazards.
Regulations concerning safety of elevators specify the minimum height of the above-mentioned toe guard as 750 mm. A problem with the use of a toe guard of such a large height is that there is not enough room for the toe guard in a low elevator shaft pit when the elevator car comes e.g. to the lowest level. In prior-art elevator solutions, various attempts have been made to address this problem, either by making pivoted toe guard structures that can turn or slide under the elevator car or also by using telescoping structures. One problem is to see to it that the toe guard will not stop the elevator car when the elevator is coming to the lowest landing level in a shaft with a low pit. In this situation the safety circuit of the toe guard has to be bypassed to allow the drive current to be supplied to the elevator even in such a case. The safety circuit also needs to be bypassed in a repair or maintenance situation where the elevator car has to be driven to a level below the lowest landing floor, e.g. down to the buffers. In these situations, however, it must be made sure that the toe guard will return to its normal position after the elevator car has moved upwards from the lowest level. One further problem is to bypass the elevator's safety circuit in a way allowing the toe guard to work well as a protective element by stopping the movement of the elevator car if the toe guard hits an obstacle, such as a person's hand, foot or body, but at the same time so that the toe guard will not stop the elevator car when the elevator descends to the lowest level in a shaft with a low pit.
European patent application no. EP1118576 discloses a toe guard that can be folded or slid under the elevator car so that the elevator car can get closer to the bottom of the shaft. The solution according to this EP solution uses complex lever arms and guides for changing the position of the toe guard. The complex structure is more expensive and is additionally susceptible to damage. However, the specification does not resent any actual safety circuit or a circuit bypassing it, so there is also the problem that the elevator car will not necessarily stop even if the toe guard should hit an obstacle e.g. at floors other than the bottom floor.
U.S. Pat. No. 6,095,288 discloses a toe guard that turns on hinges under the elevator car. In this solution, the bottom of the shaft is provided with a surface inclined at an angle of about 45° which receive rollers provided at the lower edge of the toe guard when the elevator car comes to its lowest position, with the result that the toe guard, guided by the rollers, turns on its hinges to a position under the elevator car. One problem here is that the structure can become dirty, which may prevent the toe guard from being properly returned to the straight position or block the hinges so that the turning movement of the toe guard may become stiff, leading to a risk of breakdown of the whole structure. Neither does this solution propose a safety circuit or its bypass circuit, so in respect of safety this solution involves the same problems as the solution described above.
International patent specification no. WO 02/10053 also discloses toe guard solutions to address the aforesaid problem. The embodiment presented in FIGS. 4 and 5 is a complex turnable structure, which has the above-mentioned drawbacks. FIGS. 1-3 show a solution in which the structure comprises a telescoping toe guard with an external lower part moving vertically on a fixed internal upper part. A problem with the solution described in this specification is dirt, which can easily get into the open spaces between the moving parts, causing operational disturbances. This solution, too, has the drawback that it does not propose any kind of safety circuit, so there not necessarily anything to stop the elevator when the toe guard hits an obstacle.